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Author Topic: Latest PIOMAS update (August mid monthly update)  (Read 571618 times)

magnamentis

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Re: Latest PIOMAS update (August)
« Reply #2100 on: August 07, 2017, 11:46:01 AM »
But if you are going to make grandiose claims, challenging the fundamental reliability of rigorously tested models, then you should damn well be held to the same standards as the people you are challenging – in this instance the Polar Science Center.

I don't disagree in substance.  What I would say is if you're going to pull someone up about it, then do at least make the case a bit more strongly.  PIMOAS  is a model based on data and not verified data in and of itself.

All volume models have been criticised on these boards because the enthusiast effort we see on a daily basis can, at times, make a complete nonsense of the volume models when there is patently no ice where the model says there is 2M ice or more.  Even worse when a storm kicks up and the area showing 2M ice, in whatever concentration,  suddenly vanishes in a day or two and the whole area is clear of ice.

These are statistical anomalies and they do exist in all the models.  Even more so in challenging times of rapid and fundamentally outside current understanding, rates of change in ice dynamics.

It is correct to challenge.  That is how science gets better.  But it is also a requirement to provide the evidence of where the model is failing, so that those who work with the models can work out why it failed.

As you say most of us do this as a hobby and very few subject their comments to rigorous statistical analysis.  Most don't have the time and the rest of us wouldn't know how to anyway.

But it doesn't meant that the analysts among us can't spot inconsistencies.

I guess I'm saying educate don't berate.

all you're saying is totally correct while to repeatedly mention obvious (visible) flaws in any model can't be wrong at all. we should never settle with what we get as long as flaws are obviously present.

the problem with criticism if any is the wording of it which i know from own experience is often subject the language barriers. even people who speak a language well in daily life at times reach some limits as soon as it comes to scientific and/or most precise talks where the exact terms become more and more important, especially when it comes to criticism of any kind, including intent constructive criticism.

each of us know his true intentions but often through imperfect wording/tone the good intentions/motives get omitted to the native speakers of a language. the worst level of
language skills for high level talk is between 50 and 80% level, because once language and
orthography appears to be good, a wrong word is understood as intended while it perhaps was not.
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greatdying2

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Re: Latest PIOMAS update (August)
« Reply #2101 on: August 08, 2017, 12:06:30 AM »
Personally I am highly sceptical about any model. Useful? Definitely. Truth? Definitely not. The real question is, in what ways is it useful and in what ways is it not.

Hopefully everyone has already seen this: http://forum.arctic-sea-ice.net/index.php/topic,8.msg124238.html#msg124238
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

FishOutofWater

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Re: Latest PIOMAS update (August)
« Reply #2102 on: August 08, 2017, 01:55:01 AM »
<snip> I have forwarded your reply to AMEG. (I do not want government decision-makers to get mixed up with different time periods and draw wrong conclusions from mixing 20+ and <7 year and current season conditions.) Many thanks!

I'm a geochemist, as is Wally Broecker. I'm not an oceanographer. My problem in impersonating an oceanographer is that Wally Broecker is a much more clever and published geochemist than I am. So please don't take my word on anything oceanographic. Wally was smart enough that he could tell a great story about the global conveyor belt for salt and heat. I'm not that smart. Verify my words. My scientific career impressed no one.

For your information I worked on nuclear waste disposal safety research program development and project management after earning my PhD in geochemistry. I have dealt with difficult interdisciplinary problems, but my publication list is very short. I retired early when Newt Gingrich eliminated our nuclear waste safety research program.

My user name here comes from my situation of moving from Hawaii back to the mainland. After I left U.S. govt. research, I moved to Kauai and became a pretty good body surfer for a guy in his mid forties. After 10 years on Kauai I had to move back to a low surf environment. Thus FishOutofWater.

Of course, there are multiple other meanings to the name I have been using for many years at Dailykos where my writing has been pretty popular. I kept that user name for this blog so people would know who I was on the internet.

As for PIOMAS, it isn't perfect, but it appears to reflect reality better than any other model.

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2103 on: August 18, 2017, 09:19:04 AM »
The mid monthly update for August of PIOMAS gridded thickness data is here, 1-15 August.

The race with 2012 seems lost: at 15th August volume was 0.48 [1000km3 ] above 2012.

Here is my calculated volume for August 1-15:
 [1] 6.627 6.506 6.390 6.301 6.175 6.033 5.944 5.876 5.795 5.703 5.628 5.555
[13] 5.492 5.436 5.376

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2104 on: August 18, 2017, 09:25:31 AM »
Here is the animation for July and half of August.

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2105 on: August 18, 2017, 10:16:30 AM »
Thickness map, compared with previous years on 15th August.

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2106 on: August 18, 2017, 10:52:11 AM »
Daily Fram im/export will not surprise anyone.

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2107 on: August 18, 2017, 10:58:05 AM »

Wipneus

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2108 on: August 18, 2017, 11:01:16 AM »
Daily volume and volume-anomaly graphs, updated with this data.

Pavel

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2109 on: August 18, 2017, 12:38:59 PM »
 Thanks Wipneus. The question is how mild will be the freezing season. Precondition is worse than 2016 - lower volume, higher SSTs,  the thickest ice is on Atlantic side. There was no GACs in summer but thereby more ocean heat could be stored for winter. If the freezing season ends worse than this year, it will be harder to avoid a cannonball in summer
« Last Edit: August 18, 2017, 12:46:16 PM by Pavel »

DrTskoul

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2110 on: August 18, 2017, 01:30:48 PM »
Negative feedbacks have shown their hand. New records have been avoided by the thinnest of margins, yet they have also revealed that the best we can hope for is for negative feedbacks to slow down the freight train from crashing. But crash it will....
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
― Richard P. Feynman

Neven

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2111 on: August 19, 2017, 12:50:44 AM »
Thanks, Wip. A fascinating melting season. Looking at the comparison maps:

the thickest ice is on Atlantic side.

Indeed.
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greatdying2

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2112 on: August 19, 2017, 02:29:24 AM »
Thanks Wipneus. A very useful update, as always.

It's worth keeping these in mind. I note that PIOMAS has not corrected the large anomaly near Svalbard -- will this now be perpetuated into the freezing season? I wonder if they are considering updating PIOMAS to assimilate CryoSat data...
« Last Edit: August 19, 2017, 02:37:33 AM by greatdying2 »
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

oren

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2113 on: August 19, 2017, 09:07:57 PM »
The Arctic has dodged a cannonball indeed this year. July and mid-August were cool, while the ice was at its relative thinnest and waiting for the death blow. Fortunately it never came.
The first chart is the "forecast" made at the end of June, taking the low end of the losses sustained by the four low years (2010, 2011, 2012, 2016) in each two-week period.
The second chart shows the actual numbers til mid-Aug (day 227), much higher than the simplistic forecast. A slowdown is apparent from mid-July (day 196). From record low to 3rd place, indeed something I had not expected. Even the 2017 cyclone in early August is barely felt on the chart.
(Inner Basin = CAB, CAA, Chukchi, Beaufort, ESS, Laptev.)
The third chart shows the outer periphery progression, where a July slowdown can also be seen.
A fourth chart shows where 2017 is currently record low after previously lagging behind - the Greenland Sea. The halt in Fram export had some consequences after all.

iceman

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2114 on: August 21, 2017, 06:00:10 PM »
   ....
A fourth chart shows where 2017 is currently record low after previously lagging behind - the Greenland Sea. The halt in Fram export had some consequences after all.

Looks like you nailed it.  Early in melt season I thought the high Fram export would lead to accelerated ice loss in the nearby CAB.  But that didn't happen, maybe owing to snow cover from those late-winter storms.  Could be a form of negative feedback.

Thomas Barlow

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2115 on: August 21, 2017, 07:07:21 PM »
The Arctic has dodged a cannonball indeed this year. July and mid-August were cool, while the ice was at its relative thinnest and waiting for the death blow. Fortunately it never came.
Great information. Thanks.

And yet, if we take out the CAA, and thick ice (usual red crushed up against N. Greenland and north of CAA, removed) as I have shown below - or the "bits of ice left stuck to land" as Peter Wadhams puts it, regaurding a future "blue ocean" situation - then the overall Arctic Ocean may have had its worst year of volume yet.

20 Aug 2012 left.
19 Aug 2017 right
« Last Edit: Today at 04:58:29 PM by Thomas Barlow »

Thomas Barlow

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2116 on: August 21, 2017, 07:31:02 PM »
And similarly bad situation for Arctic Ocean here with HYCOM.

As above, here I took out CAA ice, and thick ice (or the "bits of ice left stuck to land" as Wadhams puts it, regaurding a future "blue ocean" situation) - black on HYCOMs thickness legend bar, taken out of chart - leaving a visual comparison of the state of overall thickness of ice in the Arctic Ocean only.

Not good.

20 Aug 2012 left.
20 Aug 2017 right
« Last Edit: Today at 05:03:30 PM by Thomas Barlow »

A-Team

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2117 on: August 21, 2017, 10:22:49 PM »
people declared the end of the melt season last year saw ice fall off a cliff last week of August ... the overall Arctic Ocean may have had its worst year of volume yet ... main thing of this melting season could be the Arctic SSTs ... it's not over 'til it's over
It's instructive to compare August 20th over the last six years using UH AMSR2. There's a lot of information lost passing from the maps to single number summary statistics. Temporal trends in map distributions may be harder to convey but that's the subject that concerns us.
« Last Edit: Today at 02:48:26 PM by A-Team »

VeliAlbertKallio

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Re: Latest PIOMAS update (August mid monthly update)
« Reply #2118 on: Today at 05:06:40 PM »
Surely, we will see thin ice eventually becoming "Hudson Bay" type ice. Peter Wadhams was pointing out long before any noticeable area reduction that sea ice was thinning based on submarine's upward sonar soundings. We may see more years of thin volatile (unpredictable!) sea ice (at the mercy of winds, waves, sunshine, & heat waves) but soon it all melts away like Hudson Bay. As a group, we must reorient ourselves beyond summer sea ice as many mitigatory actions such as sea defences, siting of nuclear reactors, etc take decades of planning in advance. Telling in the last minute there isn't any sea ice left now, therefore the land ice is destabilising fast, does not help anyone! I do not believe there is any major sea ice rebound until there is next Heindrich Ice Berg Calving event from Greenland that pumps large amounts of meltwater and slushy ice into the ocean. The flip side of this is sea level jump & a sudden failure of agriculture (the Last Dryas). Only then, I see people willing to accept the Arctic geoengineering to preserve sea ice.
« Last Edit: Today at 05:33:46 PM by VeliAlbertKallio »